A slivering device for slivering a fibre strand

Abstract

The present application belongs to the field of spinning technology equipment, and discloses a fiber sliver drawing device, which comprises front rollers and middle rollers arranged at intervals in the front-back direction, and upper and lower flexible needle belts located between the front rollers and the middle rollers; the upper flexible needle belt runs in the counterclockwise direction, and the lower flexible needle belt runs in the clockwise direction; the upper flexible needle belt is provided with multiple rows of needle teeth I and II, the same row of needle teeth I or II is arranged at intervals in the width direction of the upper flexible needle belt, and the adjacent two rows of needle teeth I and II are alternately arranged at intervals in the length direction of the upper flexible needle belt; the lower flexible needle belt is provided with multiple rows of needle teeth III and IV, the same row of needle teeth III or IV is arranged at intervals in the width direction of the upper flexible needle belt, and the adjacent two rows of needle teeth III and IV are arranged at intervals in the length direction of the lower flexible needle belt. The present application can reduce fiber damage, avoid accidental drafting and poor drafting, make the yarn evenness better, and increase the strength.

Description

Technical Field

[0001] This invention belongs to the field of spinning technology and equipment, and relates to a drawing device for fiber slivers. This invention is a divisional application of the patent with application number 2025106963896, application date May 28, 2025, entitled "A drawing method for fiber slivers". Background Technology

[0002] Drawing is a crucial step in spinning, primarily involving two processes: drawing and drafting. Drawing involves mixing and feeding multiple fiber slivers together to improve evenness and blending uniformity. Drafting elongates and thins the combined fiber aggregate, simultaneously improving fiber straightness and parallelism to enhance the strength of the spun yarn. Currently, two drawing methods are used: needleless drawing and needle-plate drawing. Needleless drawing refers to drawing where carding needles are not used to control fiber movement in the drafting zone; instead, the gripping action of rollers or aprons achieves drafting. Common methods include roller drafting and apron drafting. Needle-plate drawing uses rotating upper and lower needle plates in the drafting zone to further improve fiber straightness and parallelism, and enhance the internal structure of the yarn during drafting. Needleless drawing is typically used for cotton and cotton-type synthetic fibers, while needle-plate drawing is generally used for wool sliver spinning.

[0003] Industrial polyester staple fiber has high straightness, no crimp, and high modulus. During spinning and drawing, the interaction between fibers is relatively small, resulting in insufficient frictional force field in the drawing zone. Usually, the roller pressure needs to be increased to ensure the drawing effect, as shown in the literature (Optimization of first-stage drawing process of phenolic fiber and its influence on yarn quality [J]. Journal of Textile Research, 2016, 37(10):26-31). However, a large roller pressure will cause severe pressure on the rollers and reduce their service life. In addition, special fibers such as carbon fiber, glass fiber, horn fiber, and phenolic fiber have poor shear resistance. When subjected to large pressure from rollers and rollers, the fibers will break and suffer greater fiber damage (20-30% compared with the fiber sliver before drawing). Therefore, in order to reduce fiber breakage, a smaller roller pressure is required during spinning and drawing. However, lower roller pressure reduces the external friction field strength of the drawing and drafting device, weakening both the drafting and control forces on the fibers during drawing, which is detrimental to the smooth progress of the fiber drafting process. Simultaneously, special fibers such as carbon fiber have high modulus and high straightness (no crimp), resulting in weak interaction forces between fibers and a low internal friction field within the fiber assembly in the drafting zone. Furthermore, due to the combined effects of lower roller pressure and a weaker internal friction field, the control effect on the fibers during drafting is very weak, leading to a highly dispersed distribution of fiber speed variations. Consequently, the evenness of the fiber sliver produced after drawing does not improve but rather worsens. Moreover, the resulting fiber sliver lacks strength, leading to fiber breakage or unexpected drafting during subsequent spinning processes, severely impacting the quality of the spun yarn.

[0004] Therefore, a fiber sliver drawing device is needed to solve the above problems, which is of great significance. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art and to provide a fiber sliver drawing device.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for forming fiber slivers involves periodically repeating the following sequence at fixed positions along the fiber sliver's running path during horizontal movement of the fiber sliver: "apply force F1 → stop applying force → apply force F2 → stop applying force".

[0008] The fixed position is located between the front roller and the middle roller of the drawing frame. The pressure of the front roller is 80-250N, and the pressure of the middle roller is 150-300N. When drawing conventional raw materials, the pressure of the front roller of the drawing frame is generally 150-250N, and the pressure of the middle roller is generally 250-300N.

[0009] Force F1 is the force that causes the fiber sliver to shift horizontally to the left, and force F2 is the force that causes the fiber sliver to shift horizontally to the right.

[0010] To address the challenges of existing technologies for industrial polyester staple fibers, which exhibit high straightness, no crimp, and high modulus, but suffer from low inter-fiber friction and interaction during spinning and drawing, resulting in insufficient frictional force in the drafting zone, it is common practice to increase roller pressure to ensure drafting effectiveness. However, excessive roller pressure can severely strain the rollers, reducing their lifespan. Furthermore, when spinning and drawing specialty fibers (such as carbon fiber, glass fiber, and horn fiber), it is difficult to simultaneously reduce fiber damage and prevent accidental or poor drafting. This invention addresses these issues by maintaining normal or low roller pressure to minimize fiber damage and breakage caused by roller pressure, while simultaneously reducing fiber friction and interaction. The friction of the drafting components, especially the rollers, extends the service life of the drafting components. On the other hand, during the forward and backward movement of the fiber sliver, forces F1 and F2 are applied alternately at fixed positions along the fiber sliver's path. This causes the fibers in different length segments of the fiber sliver to undergo lateral transfer in different directions during drafting, resulting in entanglement between the fibers. Consequently, the internal frictional force field of the fiber sliver increases during drafting, which can effectively compensate for insufficient drafting force caused by low roller pressure. This increases the overall frictional strength during drafting, thereby reducing fiber damage while avoiding accidental drafting and poor drafting, resulting in better yarn evenness and higher strength.

[0011] As a preferred technical solution:

[0012] In the fiber sliver drawing method described above, the duration of each applied force F1 is 0.5-1s, the duration of each applied force F2 is 0.5-1s, and the duration of each cessation of applied force is 0.1-0.5s.

[0013] As described above, in a fiber sliver forming method, each time a force F1 is applied, the fiber sliver shifts horizontally to the left by 2-3 mm from the beginning to the end, and each time a force F2 is applied, the fiber sliver shifts horizontally to the right by 2-3 mm from the beginning to the end.

[0014] In the fiber sliver drawing method described above, the horizontal distance between the fixed position and the middle roller nip is 3-5 mm smaller than the fiber length L in the fiber sliver. When the fiber is a natural fiber, the fiber length L in the fiber sliver is the main body length of the fiber in the fiber sliver. The purpose is to ensure that the fiber sliver is stressed before acceleration. Being stressed before acceleration has two advantages: first, it allows the fiber sliver head to complete the transfer of the forward direction before acceleration. When the stretching force accelerates, the overall transfer amplitude of the fiber sliver is larger, which is more conducive to the mutual entanglement of the fiber sliver; second, the fiber sliver speed is slower before acceleration, which is more conducive to applying force to the fiber sliver, and the applied force has less impact on the stretching.

[0015] In the fiber sliver drawing method described above, the distance between the front roller nip and the middle roller nip is 8-12 mm greater than the length L of the fiber in the fiber sliver. When the fiber is a natural fiber, the length L of the fiber in the fiber sliver is the main length of the fiber in the fiber sliver.

[0016] In the fiber sliver drawing method described above, the linear speed of the middle roller is 3-6 m / min, and the ratio of the linear speed of the front roller to the linear speed of the middle roller is 3-8.

[0017] The fiber sliver forming method described above, wherein the fiber in the fiber sliver is one or more of industrial polyester staple fiber, carbon fiber, phenolic fiber, horn fiber and glass fiber.

[0018] As described in any of the preceding methods for forming fiber slivers, applying force F1 or force F2 to the fiber sliver means simultaneously puncturing the upper and lower surfaces of the fiber sliver with a puncture depth of 1-2 mm. The puncture depth should not be too large, otherwise the fibers will not be able to detach from the needle teeth in time, and the needle teeth will carry the fibers away, affecting the drafting. When applying force to the fiber sliver by puncturing, if the force is only applied to one side of the fiber sliver, the force cannot be fully applied to all fibers when the puncture depth is small.

[0019] The present invention also provides a fiber sliver drawing device, comprising a front roller and a middle roller arranged at a distance along the front-to-back direction, and further comprising an upper flexible needle belt and a lower flexible needle belt located simultaneously between the front roller and the middle roller;

[0020] The pressure of the front roller is 80-250N, and the pressure of the middle roller is 150-300N;

[0021] The upper flexible needle band moves counterclockwise, and the lower flexible needle band moves clockwise.

[0022] The upper flexible needle belt is provided with multiple rows of needle teeth I and multiple rows of needle teeth II. The same row of needle teeth I or the same row of needle teeth II are arranged at intervals along the width direction of the upper flexible needle belt, and adjacent rows of needle teeth I and needle teeth II are arranged alternately at intervals along the length direction of the upper flexible needle belt.

[0023] The lower flexible needle belt is provided with multiple rows of needle teeth III and multiple rows of needle teeth IV. The same row of needle teeth III or the same row of needle teeth IV are arranged at intervals along the width direction of the upper flexible needle belt, and adjacent rows of needle teeth III and needle teeth IV are arranged at intervals along the length direction of the lower flexible needle belt.

[0024] Needle I and needle III together apply a force F1 to the fiber sliver, which is the force that causes the fiber sliver to shift horizontally to the left.

[0025] Needle teeth II and IV together apply a force F2 to the fiber sliver, which is the force that causes the fiber sliver to shift horizontally to the right.

[0026] As a preferred technical solution:

[0027] As described above, in a fiber sliver forming device, when the needle tooth I moves to the bottom, the needle tooth I is vertically downward, and the minimum distance between the needle tooth I and the edge of the upper flexible needle belt gradually increases along the running direction of the upper flexible needle belt. Simultaneously, the needle tooth III moves to the top, the needle tooth III is vertically upward, and the minimum distance between the needle tooth III and the edge of the lower flexible needle belt gradually increases along the running direction of the lower flexible needle belt. The needle teeth I and the needle teeth III intersect each other and are arranged in a staggered manner, mimicking the crossed fingers when the hands are clasped together.

[0028] When the needleless section of the upper flexible needle belt reaches the bottom, the needleless section of the lower flexible needle belt simultaneously reaches the top.

[0029] When needle tooth II reaches the bottom, it moves vertically downwards. The minimum distance between needle tooth II and the edge of the upper flexible needle band gradually decreases along the running direction of the upper flexible needle band. Simultaneously, needle tooth IV moves to the top, moving vertically upwards. The minimum distance between needle tooth IV and the edge of the lower flexible needle band gradually decreases along the running direction of the lower flexible needle band. Needle teeth II and IV intersect each other, arranged in a staggered left-right pattern, mimicking the crossed fingers when hands are clasped together.

[0030] In the fiber sliver forming device described above, the spacing between the same row of needle teeth I or the same row of needle teeth II along the width direction of the upper flexible needle belt is 0.05-0.1 mm, the spacing between two adjacent rows of needle teeth I and II along the length direction of the upper flexible needle belt is 1.1-5.6 mm, the spacing between the same row of needle teeth III or the same row of needle teeth IV along the width direction of the lower flexible needle belt is 0.05-0.1 mm, and the spacing between two adjacent rows of needle teeth III and IV along the length direction of the lower flexible needle belt is 1.1-5.6 mm.

[0031] In the fiber sliver drawing device described above, the extended lines of the intersection of needle tooth I and the upper flexible needle belt, as well as the extended lines of the intersection of needle tooth II and the upper flexible needle belt, all form an angle of 15-20° with the edge line of the upper flexible needle belt. Similarly, the extended lines of the intersection of needle tooth III and the lower flexible needle belt, as well as the extended lines of the intersection of needle tooth IV and the lower flexible needle belt, all form an angle of 15-20° with the edge line of the lower flexible needle belt.

[0032] As described above, in a fiber sliver forming device, needle teeth I, II, III, and IV are all irregular right-angled sector plates. The irregular right-angled sector is composed of two line segments and an arc. One end of the two line segments is connected, and the other end is connected to both ends of the arc. The two line segments are perpendicular to each other. The lengths of needle teeth I and II along the length direction of the upper flexible needle belt are 5.5-11.2 mm, and the lengths of needle teeth III and IV along the length direction of the lower flexible needle belt are 5.5-11.2 mm. The tooth height (i.e., the vertical distance between the bottom end and the top end of the needle tooth) of needle teeth I, II, III, and IV is 3-5 mm, and the tooth thickness is 0.01-0.02 mm.

[0033] As described above, in a fiber sliver drawing device, the upper flexible needle belt runs at a speed of 3.7-7 m / min, and the lower flexible needle belt runs at the same speed as the upper flexible needle belt.

[0034] The fiber sliver drawing device described above further includes an upper drive roller, an upper tension roller, an upper positioning roller, a lower drive roller, a lower tension roller, and a lower positioning roller, all located simultaneously between the front roller and the middle roller.

[0035] The upper drive wheel and the upper tension wheel are arranged at intervals along the front-to-back direction, and the upper positioning wheel is located below both the upper drive wheel and the upper tension wheel. The upper flexible needle belt is simultaneously wrapped around the upper drive wheel, the upper tension wheel, and the upper positioning wheel.

[0036] The lower positioning wheel is located below the upper positioning wheel. The lower drive wheel and the lower tension wheel are arranged at intervals along the front-to-back direction. The lower positioning wheel is located above both the lower drive wheel and the lower tension wheel. The lower flexible needle belt is simultaneously wrapped around the lower positioning wheel, the lower drive wheel, and the lower tension wheel.

[0037] The fiber sliver drawing device described above further includes an upper cleaning roller and a lower cleaning roller; the upper cleaning roller is located above both the upper drive wheel and the upper tension wheel, and the lower cleaning roller is located below both the lower drive wheel and the lower tension wheel.

[0038] The fiber sliver drawing device described above further includes an upper combing needle box without a sealing surface at the bottom and a lower combing needle box without a sealing surface at the top; the upper cleaning roller, upper drive wheel, upper tension wheel and upper positioning wheel are all located in the upper combing needle box; the lower positioning wheel, lower drive wheel, lower tension wheel and lower cleaning roller are all located in the lower combing needle box.

[0039] In the fiber sliver drawing device described above, the linear speed of the middle roller is 3-6 m / min, and the ratio of the linear speed of the front roller to the linear speed of the middle roller is 3-8 times.

[0040] Beneficial effects:

[0041] (1) By controlling the roller pressure to be relatively low, the present invention can reduce the damage and breakage of the fiber caused by the roller pressure, and at the same time reduce the friction of the fiber on the drafting components, especially the leather roller, thus extending the service life of the drafting components.

[0042] (2) During the forward and backward movement of the fiber sliver, the present invention applies forces F1 and F2 alternately at fixed positions on the fiber sliver's running path, causing the fibers in different length segments of the fiber sliver to undergo lateral transfer in different directions during drafting. The fibers become entangled with each other, thereby increasing the internal friction field of the fiber sliver (i.e., the interaction between fibers) during drafting. This can effectively compensate for the problem of insufficient drafting force caused by low roller pressure, increase the total friction boundary strength during drafting, thereby reducing fiber damage while avoiding accidental drafting and poor drafting, resulting in better yarn evenness and higher strength.

[0043] (3) The fibers in the special fiber strip produced by the present invention have sufficient bonding force, thereby solving the problem of insufficient strength of special fibers such as carbon fiber strips, effectively improving the quality of yarns such as evenness, making them less prone to breakage and less prone to accidental stretching during subsequent applications. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the fiber sliver drawing device of the present invention;

[0045] Figure 2 This is a schematic diagram of the needle teeth mating of the upper and lower flexible needle bands of the present invention;

[0046] Figure 3 This is a schematic diagram of the arrangement of the needle teeth on the upper flexible needle belt of the present invention;

[0047] Figure 4 This is a schematic diagram of the needle teeth I and II of the flexible needle tape of the present invention;

[0048] Figure 5 This is a schematic diagram of the needle tooth arrangement and spacing of the present invention; in the figure, a represents the length of the needle tooth along the forward direction of the flexible needle strip, b represents the spacing between adjacent needle teeth along the forward direction of the flexible needle strip, and c represents the tooth length of the needle tooth.

[0049] Figure 6 This is a schematic diagram illustrating the principle of the fiber sliver forming method of the present invention;

[0050] In the diagram, 1-front roller, 2-middle roller, 3-upper comb needle box, 4-lower comb needle box, 5-upper flexible needle belt, 6-lower flexible needle belt, 7-needle tooth I, 8-needle tooth II, 9-needle tooth III, 10-needle tooth IV, 11-upper drive wheel, 12-upper tension wheel, 13-upper positioning wheel, 14-upper cleaning roller, 15-lower drive wheel, 16-lower tension wheel, 17-lower positioning wheel, 18-lower cleaning roller, 19-fiber sliver. Detailed Implementation

[0051] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0052] To ensure that the performance of the substances used in each embodiment and comparative example is fully disclosed, the manufacturers and brands of the substances are specified. Other manufacturers and brands that conform to the limitations of this invention are also feasible.

[0053] The test methods for the relevant performance indicators of the following embodiments and comparative examples are as follows:

[0054] Evenness: The fiber slivers after leaving the front roller nipper in each embodiment were used as samples, and the samples were measured by capacitance method according to GB / T3292.1-2008.

[0055] Fiber damage rate: The fiber slivers after leaving the front roller jaws in each embodiment were used as samples. The length distribution of fibers in the samples and the fiber slivers before sizing were measured using the GB19617-2007 standard. Short fibers were defined as fibers with a length <15mm. The fiber damage rate was then calculated based on the measurement results, using the following formula:

[0056]

[0057] Example 1

[0058] A fiber sliver drawing device, such as Figures 1-5 As shown, it includes a front roller 1 and a middle roller 2 arranged at intervals along the front-to-back direction, an upper flexible needle belt 5 and a lower flexible needle belt 6 located between the front roller 1 and the middle roller 2, an upper cleaning roller 14, a lower cleaning roller 18, an upper comb needle box 3 with no sealing surface at the bottom, a lower comb needle box 4 with no sealing surface at the top, an upper drive wheel 11, an upper tension wheel 12, an upper positioning wheel 13, a lower drive wheel 15, a lower tension wheel 16 and a lower positioning wheel 17;

[0059] The pressure of front roller 1 is 80-250N, and the pressure of middle roller 2 is 150-300N;

[0060] The linear velocity of the middle roller 2 is 3-6 m / min, and the ratio of the linear velocity of the front roller 1 to the linear velocity of the middle roller 2 is 3-8.

[0061] The upper cleaning roller 14, upper drive wheel 11, upper tension wheel 12 and upper positioning wheel 13 are all located in the upper comb needle box 3; the lower positioning wheel 17, lower drive wheel 15, lower tension wheel 16 and lower cleaning roller 18 are all located in the lower comb needle box 4.

[0062] The upper drive wheel 11 and the upper tension wheel 12 are arranged at intervals along the front-to-back direction, and the upper positioning wheel 13 is located below both the upper drive wheel 11 and the upper tension wheel 12.

[0063] The lower positioning wheel 17 is located below the upper positioning wheel 13, the lower transmission wheel 15 and the lower tension wheel 16 are arranged at intervals in the front-to-back direction, and the lower positioning wheel 17 is located above both the lower transmission wheel 15 and the lower tension wheel 16.

[0064] The upper cleaning roller 14 is located above both the upper drive roller 11 and the upper tension roller 12, and the lower cleaning roller 18 is located below both the lower drive roller 15 and the lower tension roller 16.

[0065] like Figures 1-3 As shown, the upper flexible needle belt 5 is provided with multiple rows of needle teeth I7 and multiple rows of needle teeth II8;

[0066] The same row of needle teeth I7 or the same row of needle teeth II8 are arranged at intervals along the width direction of the upper flexible needle strip 5, and the spacing between the same row of needle teeth I7 or the same row of needle teeth II8 along the width direction of the upper flexible needle strip 5 is 0.05-0.1mm;

[0067] The adjacent rows of needle teeth I7 and needle teeth II8 are arranged alternately along the length of the upper flexible needle strip 5, and the spacing between the adjacent rows of needle teeth I7 and needle teeth II8 along the length of the upper flexible needle strip 5 is 1.1-5.6mm;

[0068] The extended lines of the intersection of needle tooth I7 and the upper flexible needle strip 5, as well as the extended lines of the intersection of needle tooth II8 and the upper flexible needle strip 5, all form an angle of 15-20° with the edge line of the upper flexible needle strip 5.

[0069] The lengths of needle teeth I7 and II8 along the length direction of the upper flexible needle band 5 are 5.5-11.2 mm;

[0070] The upper flexible needle belt 5 is simultaneously fitted onto the upper transmission wheel 11, the upper tension wheel 12, and the upper positioning wheel 13; the upper flexible needle belt 5 runs in a counterclockwise direction, and the running speed of the upper flexible needle belt 5 is 3.7-7m / min;

[0071] The lower flexible needle belt 6 is provided with multiple rows of needle teeth Ⅲ9 and multiple rows of needle teeth Ⅳ10;

[0072] The same row of needle teeth Ⅲ9 or the same row of needle teeth Ⅳ10 are arranged at intervals along the width direction of the upper flexible needle strip 5, and the spacing between the same row of needle teeth Ⅲ9 or the same row of needle teeth Ⅳ10 along the width direction of the lower flexible needle strip 6 is 0.05-0.1mm.

[0073] The adjacent rows of needle teeth Ⅲ9 and needle teeth Ⅳ10 are arranged at intervals along the length direction of the lower flexible needle strip 6, and the spacing between the adjacent rows of needle teeth Ⅲ9 and needle teeth Ⅳ10 along the length direction of the lower flexible needle strip 6 is 1.1-5.6mm;

[0074] The extended lines of the intersection of needle tooth Ⅲ9 and lower flexible needle strip 6, as well as the extended lines of the intersection of needle tooth Ⅳ10 and lower flexible needle strip 6, all form an angle of 15-20° with the edge line of lower flexible needle strip 6.

[0075] The lengths of needle teeth III9 and IV10 along the length direction of the lower flexible needle band 6 are 5.5-11.2 mm;

[0076] The lower flexible needle belt 6 is simultaneously fitted onto the lower positioning wheel 17, the lower transmission wheel 15, and the lower tensioning wheel 16;

[0077] The lower flexible needle belt 6 runs in a clockwise direction, and the running speed of the lower flexible needle belt 6 is the same as the running speed of the upper flexible needle belt 5.

[0078] Needle I7, Needle II8, Needle III9 and Needle IV10 are all irregular right-angled sector plates. The irregular right-angled sector is composed of two line segments and one arc. One end of the two line segments is connected, and the other end is connected to the two ends of the arc respectively. The two line segments are perpendicular to each other.

[0079] like Figure 2 , Figure 4 , Figure 5 As shown, the tooth height of needle tooth I7, needle tooth II8, needle tooth III9 and needle tooth IV10 is 3-5mm, and the tooth thickness is 0.01-0.02mm;

[0080] When needle tooth I7 moves to the bottom, needle tooth I7 moves vertically downward. The minimum distance between needle tooth I7 and the edge of the upper flexible needle band 5 gradually increases along the running direction of the upper flexible needle band 5. Needle tooth III9 moves to the top at the same time. Needle tooth III9 moves vertically upward. The minimum distance between needle tooth III9 and the edge of the lower flexible needle band 6 gradually increases along the running direction of the lower flexible needle band 6. Needle tooth I7 and needle tooth III9 intersect each other.

[0081] like Figure 1 , Figure 2 , Figure 6 As shown, needle teeth I7 and III9 together apply force F1 to fiber sliver 19, and fiber sliver 19 shifts horizontally to the left under the action of force F1;

[0082] When the needleless section of the upper flexible needle belt 5 reaches the bottom, the needleless section of the lower flexible needle belt 6 simultaneously reaches the top.

[0083] When needle tooth II8 moves to the bottom, needle tooth II8 moves vertically downward. The minimum distance between needle tooth II8 and the edge of the upper flexible needle band 5 gradually decreases along the running direction of the upper flexible needle band 5. Needle tooth IV10 moves synchronously to the top, needle tooth IV10 moves vertically upward. The minimum distance between needle tooth IV10 and the edge of the lower flexible needle band 6 gradually decreases along the running direction of the lower flexible needle band 6. Needle tooth II8 and needle tooth IV10 intersect each other.

[0084] Needle teeth II8 and IV10 together apply force F2 to fiber sliver 19, causing fiber sliver 19 to shift horizontally to the right under the action of force F2.

[0085] Comparative Example 1

[0086] A fiber sliver drawing device is basically the same as in Embodiment 1, except that it does not have an upper flexible needle belt and a lower flexible needle belt.

[0087] Comparative Example 2

[0088] A fiber sliver drawing device is basically the same as in Embodiment 1, except that it does not have an upper flexible needle tape.

[0089] Comparative Example 3

[0090] A fiber sliver drawing device is basically the same as in Embodiment 1, except that: the upper flexible needle belt has no needle teeth I, and the lower flexible needle belt has no needle teeth III.

[0091] Example 2

[0092] A method for drawing fiber slivers involves the following steps: During the horizontal movement of the fiber sliver (the fiber in the fiber sliver is industrial polyester staple fiber, manufactured by Jiangsu Hengli Chemical Fiber Co., Ltd., with a specification of 1.67 dtex and a length L of 51 mm) in the front-to-back direction, at a fixed position along the fiber sliver's path, the drawing device of Example 1 is used to periodically repeat the operation of "applying force F1 → stopping applying force → applying force F2 → stopping applying force"; wherein:

[0093] The fiber sliver contains 8 fibers, and the weight of a single fiber is 18g / 5m.

[0094] The pressure of the front roller is 250N, the pressure of the middle roller is 300N, the linear speed of the middle roller is 6m / min, the ratio of the linear speed of the front roller to the linear speed of the middle roller is 5, and the running speed of the upper flexible needle belt is 6.7m / min.

[0095] The duration of each application of force F1 is 0.5s, the duration of each application of force F2 is 0.5s, and the duration of each cessation of application of force is 0.1s.

[0096] Each time force F1 is applied, the fiber sliver shifts horizontally to the left by 2 mm from the beginning to the end; each time force F2 is applied, the fiber sliver shifts horizontally to the right by 2 mm from the beginning to the end.

[0097] Applying force F1 or force F2 to the fiber sliver means simultaneously puncturing the upper and lower surfaces of the fiber sliver to a depth of 1.6 mm.

[0098] The parameter settings for the drawing frame used are as follows:

[0099] The distance between the front roller jaws and the middle roller jaws is 9 mm greater than the length L of the fiber in the fiber sliver;

[0100] The horizontal distance between the fixed position and the middle roller jaws is 4mm smaller than the length L of the fiber in the fiber sliver;

[0101] The spacing between the needle teeth I in the same row along the width direction of the upper flexible needle strip is 0.05mm, and the spacing between the needle teeth II in the same row along the width direction of the upper flexible needle strip is 0.05mm.

[0102] The spacing between two adjacent rows of needle teeth I and needle teeth II along the length of the upper flexible needle strip is 1.1 mm;

[0103] The lengths of needle teeth I and II along the length of the upper flexible needle strip are 5.5 mm;

[0104] The extended lines of the intersection of needle tooth I and the upper flexible needle strip, as well as the extended lines of the intersection of needle tooth II and the upper flexible needle strip, all form an angle of 20° with the edge line of the upper flexible needle strip;

[0105] The spacing between the needle teeth III in the same row along the width direction of the lower flexible needle strip is 0.05 mm, and the spacing between the needle teeth IV in the same row along the width direction of the lower flexible needle strip is 0.05 mm.

[0106] The spacing between two adjacent rows of needle teeth III and IV along the length of the lower flexible needle strip is 1.1 mm;

[0107] The lengths of needle teeth III and IV along the length of the lower flexible needle band are 5.5 mm;

[0108] The extended lines of the intersection of needle tooth III and the lower flexible needle strip, as well as the extended lines of the intersection of needle tooth IV and the lower flexible needle strip, all form an angle of 20° with the edge line of the lower flexible needle strip.

[0109] The tooth lengths of needle teeth I, II, III, and IV are all 5.9 mm;

[0110] The tooth height of needle tooth I, needle tooth II, needle tooth III and needle tooth IV is 3 mm, and the tooth thickness is 0.01 mm.

[0111] The weight of the fiber sliver after leaving the front roller nip is 15g / 5m, the unevenness rate is 8%, and the fiber damage rate is 1% compared with the fiber sliver before drawing.

[0112] Example 3

[0113] A method for drawing fiber slivers involves the following steps: During the horizontal movement of the fiber sliver (the fibers in the fiber sliver are carbon fiber, manufactured by Zhongfu Shenying Carbon Fiber Co., Ltd., grade SYT45, length L is 51mm) in the front-to-back direction, at a fixed position along the fiber sliver's path, the drawing device of Example 1 is used to periodically repeat the operation on the fiber sliver in the sequence of "applying force F1 → stopping applying force → applying force F2 → stopping applying force"; wherein:

[0114] The fiber sliver contains 6 fibers, and the weight of a single fiber is 16g / 5m.

[0115] The pressure of the front roller is 80N, the pressure of the middle roller is 150N, the linear speed of the middle roller is 3m / min, the ratio of the linear speed of the front roller to the linear speed of the middle roller is 8, and the running speed of the upper flexible needle belt is 3.7m / min.

[0116] The duration of each application of force F1 is 1 second, the duration of each application of force F2 is 1 second, and the duration of each cessation of application of force is 0.5 seconds.

[0117] Each time force F1 is applied, the fiber sliver shifts horizontally to the left by 3 mm from the beginning to the end; each time force F2 is applied, the fiber sliver shifts horizontally to the right by 3 mm from the beginning to the end.

[0118] Applying force F1 or force F2 to the fiber sliver means simultaneously puncturing the upper and lower surfaces of the fiber sliver to a depth of 2 mm.

[0119] The parameter settings for the drawing frame used are as follows:

[0120] The distance between the front roller jaws and the middle roller jaws is 12 mm greater than the length L of the fiber in the fiber sliver;

[0121] The horizontal distance between the fixed position and the middle roller jaws is 3mm smaller than the length L of the fiber in the fiber sliver;

[0122] The spacing between the needle teeth I in the same row along the width direction of the upper flexible needle strip is 0.1 mm, and the spacing between the needle teeth II in the same row along the width direction of the upper flexible needle strip is 0.1 mm.

[0123] The spacing between two adjacent rows of needle teeth I and needle teeth II along the length of the upper flexible needle strip is 5.6 mm;

[0124] The lengths of needle teeth I and II along the length of the upper flexible needle strip are 11.2 mm;

[0125] The extended lines of the intersection of needle tooth I and the upper flexible needle strip, as well as the extended lines of the intersection of needle tooth II and the upper flexible needle strip, all form an angle of 15° with the edge line of the upper flexible needle strip;

[0126] The spacing between the needle teeth III in the same row along the width direction of the lower flexible needle strip is 0.1 mm, and the spacing between the needle teeth IV in the same row along the width direction of the lower flexible needle strip is 0.1 mm.

[0127] The spacing between two adjacent rows of needle teeth III and IV along the length of the lower flexible needle strip is 5.6 mm;

[0128] The lengths of needle teeth III and IV along the length of the lower flexible needle band are 11.2 mm;

[0129] The extended lines of the intersection of needle tooth III and the lower flexible needle strip, as well as the extended lines of the intersection of needle tooth IV and the lower flexible needle strip, all form an angle of 15° with the edge line of the lower flexible needle strip.

[0130] The tooth lengths of needle teeth I, II, III, and IV are all 11.6 mm;

[0131] The tooth height of needle tooth I, needle tooth II, needle tooth III and needle tooth IV is 5 mm, and the tooth thickness is 0.02 mm.

[0132] The weight of the fiber sliver after leaving the front roller nip is 13.5 g / 5 m, the unevenness rate is 12%, and the fiber damage rate is 10% compared with the fiber sliver before drawing.

[0133] Comparative Example 4

[0134] A fiber sliver drawing device is basically the same as in Example 3, except that it uses the drawing device of Comparative Example 1.

[0135] The unevenness of the fiber sliver after leaving the front roller jaws was 21%.

[0136] Comparing Example 3 with Comparative Example 4, it can be seen that the fiber sliver in Comparative Example 4 has a poorer evenness rate after leaving the front roller nip. This is because in Example 3, forces F1 and F2 can be applied alternately to the fiber sliver, causing the fibers in different length segments of the fiber sliver to undergo lateral transfer in different directions during drafting. The fibers become entangled with each other, which increases the internal friction field of the fiber sliver during drafting. This can effectively compensate for the insufficient drafting force caused by the low roller pressure, and increase the total friction boundary strength during drafting. This reduces fiber damage while avoiding accidental drafting and poor drafting, resulting in better yarn evenness and improved evenness rate. In contrast, forces F1 and F2 cannot be applied to the fibers in Comparative Example 4 during the drawing process, resulting in a poorer evenness rate of the fiber sliver after leaving the front roller nip.

[0137] Comparative Example 5

[0138] A fiber sliver drawing device is basically the same as in Example 3, except that it uses the drawing device of Comparative Example 2.

[0139] The unevenness of the fiber sliver after leaving the front roller jaws was 17%.

[0140] Comparing Example 3 with Comparative Example 5, it can be seen that the fiber sliver in Comparative Example 5 has a poorer evenness rate after leaving the front roller nip. This is because the fibers in Comparative Example 5 are only subjected to the action of the lower flexible needle belt teeth during the drawing process, resulting in a smaller number of fibers subjected to the force. This leads to insufficient internal friction field of the fiber sliver during drawing, which cannot increase the total friction boundary strength during drawing, resulting in a smaller degree of improvement in drawing unevenness. Ultimately, this leads to a reduction in the evenness rate of the fiber sliver after leaving the front roller nip.

[0141] Comparative Example 6

[0142] A fiber sliver drawing device is basically the same as in Example 3, except that it uses the drawing device of Comparative Example 3.

[0143] The unevenness of the fiber sliver after leaving the front roller jaws was 16.5%.

[0144] Comparing Example 3 with Comparative Example 6, it can be seen that the fiber sliver in Comparative Example 6 has a poorer evenness rate after leaving the front roller nip. This is because the fiber in Comparative Example 6 is only subjected to a force in one direction during the drawing process, which makes the enhancement of the internal friction field of the fiber not large enough, and the degree of improvement in stretching unevenness is small, ultimately leading to a reduction in the evenness rate of the fiber sliver after leaving the front roller nip.

[0145] Example 4

[0146] A method for drawing fiber slivers involves the following steps: During the horizontal movement of the fiber sliver (the fiber in the fiber sliver is phenolic fiber, manufactured by Gunei Chemicals Co., Ltd. of Japan, grade KF0730, length L is 55mm) in the front-to-back direction, at a fixed position along the fiber sliver's path, the drawing device of Example 1 is used to periodically repeat the operation on the fiber sliver in the sequence of "applying force F1 → stopping applying force → applying force F2 → stopping applying force"; wherein:

[0147] The fiber sliver contains 6 fibers, and the weight of a single fiber is 16.5g / 5m.

[0148] The pressure of the front roller is 150N, the pressure of the middle roller is 200N, the linear speed of the middle roller is 4m / min, the ratio of the linear speed of the front roller to the linear speed of the middle roller is 6, and the running speed of the upper flexible needle belt is 4.65m / min.

[0149] The duration of each application of force F1 is 0.8s, the duration of each application of force F2 is 0.8s, and the duration of each cessation of application of force is 0.4s.

[0150] Each time force F1 is applied, the fiber sliver shifts horizontally to the left by 2.5 mm from the beginning to the end; each time force F2 is applied, the fiber sliver shifts horizontally to the right by 2.5 mm from the beginning to the end.

[0151] Applying force F1 or force F2 to the fiber sliver means simultaneously puncturing the upper and lower surfaces of the fiber sliver to a depth of 1.5 mm.

[0152] The parameter settings for the drawing frame used are as follows:

[0153] The distance between the front roller jaws and the middle roller jaws is 10 mm greater than the length L of the fiber in the fiber sliver;

[0154] The horizontal distance between the fixed position and the middle roller jaws is 5mm smaller than the length L of the fiber in the fiber sliver;

[0155] The spacing between the needle teeth I in the same row along the width direction of the upper flexible needle strip is 0.08 mm, and the spacing between the needle teeth II in the same row along the width direction of the upper flexible needle strip is 0.08 mm.

[0156] The spacing between two adjacent rows of needle teeth I and II along the length of the upper flexible needle strip is 4.4 mm;

[0157] The lengths of needle teeth I and II along the length of the upper flexible needle strip are 8.7 mm;

[0158] The extended lines of the intersection of needle tooth I and the upper flexible needle strip, as well as the extended lines of the intersection of needle tooth II and the upper flexible needle strip, all form an angle of 16° with the edge line of the upper flexible needle strip.

[0159] The spacing between the needle teeth III in the same row along the width direction of the lower flexible needle strip is 0.08 mm, and the spacing between the needle teeth IV in the same row along the width direction of the lower flexible needle strip is 0.08 mm.

[0160] The spacing between two adjacent rows of needle teeth III and IV along the length of the lower flexible needle strip is 4.4 mm;

[0161] The lengths of needle teeth III and IV along the length direction of the lower flexible needle band are 8.7 mm;

[0162] The extended lines of the intersection of needle tooth III and the lower flexible needle strip, as well as the extended lines of the intersection of needle tooth IV and the lower flexible needle strip, all form an angle of 16° with the edge line of the lower flexible needle strip.

[0163] The tooth lengths of needle teeth I, II, III, and IV are all 9.1 mm;

[0164] The tooth height of needle tooth I, needle tooth II, needle tooth III and needle tooth IV is 4 mm, and the tooth thickness is 0.02 mm.

[0165] The weight of the fiber sliver after leaving the front roller nip is 14g / 5m, the unevenness rate is 10%, and the fiber damage rate is 8% compared with the fiber sliver before drawing.

[0166] Example 5

[0167] A method for drawing fiber slivers involves the following steps: During the horizontal movement of the fiber sliver (containing hornwort fibers of length L of 35mm) in the front-to-back direction, at a fixed position along the fiber sliver's path, the drawing device of Example 1 is used to periodically repeat the operation in the sequence of "applying force F1 → stopping applying force → applying force F2 → stopping applying force"; wherein:

[0168] The fiber sliver contains 6 fibers, and the weight of a single fiber is 14g / 5m;

[0169] The pressure of the front roller is 120N, the pressure of the middle roller is 180N, the linear speed of the middle roller is 5m / min, the ratio of the linear speed of the front roller to the linear speed of the middle roller is 3, and the running speed of the upper flexible needle belt is 5.8m / min.

[0170] The duration of each application of force F1 is 0.6s, the duration of each application of force F2 is 0.6s, and the duration of each cessation of application of force is 0.2s.

[0171] Each time force F1 is applied, the fiber sliver shifts horizontally to the left by 2.5 mm from the beginning to the end; each time force F2 is applied, the fiber sliver shifts horizontally to the right by 2.5 mm from the beginning to the end.

[0172] Applying force F1 or force F2 to the fiber sliver means simultaneously puncturing the upper and lower surfaces of the fiber sliver to a depth of 1 mm.

[0173] The parameter settings for the drawing frame used are as follows:

[0174] The distance between the front roller jaws and the middle roller jaws is 8 mm greater than the length L of the fiber in the fiber sliver;

[0175] The horizontal distance between the fixed position and the middle roller jaws is 3mm smaller than the length L of the fiber in the fiber sliver;

[0176] The spacing between the needle teeth I in the same row along the width direction of the upper flexible needle strip is 0.06 mm, and the spacing between the needle teeth II in the same row along the width direction of the upper flexible needle strip is 0.06 mm.

[0177] The spacing between two adjacent rows of needle teeth I and II along the length of the upper flexible needle strip is 2.7 mm;

[0178] The lengths of needle teeth I and II along the length of the upper flexible needle strip are 8 mm;

[0179] The extended lines of the intersection of needle tooth I and the upper flexible needle strip, as well as the extended lines of the intersection of needle tooth II and the upper flexible needle strip, all form an angle of 18° with the edge line of the upper flexible needle strip.

[0180] The spacing between the needle teeth III in the same row along the width direction of the lower flexible needle strip is 0.06 mm, and the spacing between the needle teeth IV in the same row along the width direction of the lower flexible needle strip is 0.06 mm.

[0181] The spacing between two adjacent rows of needle teeth III and IV along the length of the lower flexible needle strip is 2.7 mm;

[0182] The lengths of needle teeth III and IV along the length direction of the lower flexible needle strip are 8 mm;

[0183] The extended lines of the intersection of needle tooth III and the lower flexible needle strip, as well as the extended lines of the intersection of needle tooth IV and the lower flexible needle strip, all form an angle of 18° with the edge line of the lower flexible needle strip.

[0184] The tooth lengths of needle teeth I, II, III, and IV are all 8.4 mm;

[0185] The tooth height of needle tooth I, needle tooth II, needle tooth III and needle tooth IV is 3.5 mm and the tooth thickness is 0.01 mm.

[0186] The weight of the fiber sliver after leaving the front roller nip is 10g / 5m, the unevenness rate is 8%, and the fiber damage rate is 8% compared with the fiber sliver before drawing.

[0187] Example 6

[0188] A method for drawing fiber slivers involves the following steps: During the horizontal movement of the fiber sliver (the fibers in the fiber sliver are glass fibers, manufactured by Chongqing Sanlei Glass Fiber Co., Ltd., grade ECR13-2400, length L is 51mm) in the front-to-back direction, at a fixed position along the fiber sliver's path, the drawing device of Example 1 is used to periodically repeat the operation on the fiber sliver in the sequence of "applying force F1 → stopping applying force → applying force F2 → stopping applying force"; wherein:

[0189] The fiber sliver contains 8 fibers, and the weight of a single fiber is 18.5g / 5m.

[0190] The pressure of the front roller is 100N, the pressure of the middle roller is 160N, the linear speed of the middle roller is 6m / min, the ratio of the linear speed of the front roller to the linear speed of the middle roller is 4, and the running speed of the upper flexible needle belt is 7m / min.

[0191] The duration of each application of force F1 is 0.5s, the duration of each application of force F2 is 0.5s, and the duration of each cessation of application of force is 0.1s.

[0192] Each time force F1 is applied, the fiber sliver shifts horizontally to the left by 3 mm from the beginning to the end; each time force F2 is applied, the fiber sliver shifts horizontally to the right by 3 mm from the beginning to the end.

[0193] Applying force F1 or force F2 to the fiber sliver means simultaneously puncturing the upper and lower surfaces of the fiber sliver to a depth of 1.8 mm.

[0194] The parameter settings for the drawing frame used are as follows:

[0195] The distance between the front roller jaws and the middle roller jaws is 11 mm greater than the length L of the fiber in the fiber sliver;

[0196] The horizontal distance between the fixed position and the middle roller jaws is 4mm smaller than the length L of the fiber in the fiber sliver;

[0197] The spacing between the needle teeth I in the same row along the width direction of the upper flexible needle strip is 0.05mm, and the spacing between the needle teeth II in the same row along the width direction of the upper flexible needle strip is 0.05mm.

[0198] The spacing between two adjacent rows of needle teeth I and needle teeth II along the length of the upper flexible needle strip is 1.7 mm;

[0199] The lengths of needle teeth I and II along the length of the upper flexible needle strip are 8.5 mm;

[0200] The extended lines of the intersection of needle tooth I and the upper flexible needle strip, as well as the extended lines of the intersection of needle tooth II and the upper flexible needle strip, all form an angle of 20° with the edge line of the upper flexible needle strip;

[0201] The spacing between the needle teeth III in the same row along the width direction of the lower flexible needle strip is 0.05 mm, and the spacing between the needle teeth IV in the same row along the width direction of the lower flexible needle strip is 0.05 mm.

[0202] The spacing between two adjacent rows of needle teeth III and IV along the length of the lower flexible needle strip is 1.7 mm;

[0203] The lengths of needle teeth III and IV along the length direction of the lower flexible needle strip are 8.5 mm;

[0204] The extended lines of the intersection of needle tooth III and the lower flexible needle strip, as well as the extended lines of the intersection of needle tooth IV and the lower flexible needle strip, all form an angle of 20° with the edge line of the lower flexible needle strip.

[0205] The tooth lengths of needle teeth I, II, III, and IV are all 8.8 mm;

[0206] The tooth height of needle tooth I, needle tooth II, needle tooth III and needle tooth IV is 3 mm, and the tooth thickness is 0.01 mm.

[0207] The weight of the fiber sliver after leaving the front roller nip is 15g / 5m, the unevenness rate is 11.5%, and the fiber damage rate is 10% compared with the fiber sliver before drawing.

Claims

1. A fiber sliver drawing device, comprising a front roller (1) and a middle roller (2) arranged at intervals along the front-to-back direction, characterized in that, It also includes an upper flexible needle band (5) and a lower flexible needle band (6) located simultaneously between the front roller (1) and the middle roller (2); The pressure of the front roller (1) is 80-250N, and the pressure of the middle roller (2) is 150-300N; The upper flexible needle band (5) runs counterclockwise, and the lower flexible needle band (6) runs clockwise. The upper flexible needle belt (5) is provided with multiple rows of needle teeth I (7) and multiple rows of needle teeth II (8). The same row of needle teeth I (7) or the same row of needle teeth II (8) are arranged at intervals along the width direction of the upper flexible needle belt (5), and adjacent rows of needle teeth I (7) and needle teeth II (8) are arranged alternately at intervals along the length direction of the upper flexible needle belt (5). The lower flexible needle belt (6) is provided with multiple rows of needle teeth Ⅲ (9) and multiple rows of needle teeth Ⅳ (10). The same row of needle teeth Ⅲ (9) or the same row of needle teeth Ⅳ (10) are arranged at intervals along the width direction of the upper flexible needle belt (5), and adjacent rows of needle teeth Ⅲ (9) and needle teeth Ⅳ (10) are arranged at intervals along the length direction of the lower flexible needle belt (6). Needle teeth I (7) and needle teeth III (9) together apply force F1 to the fiber sliver, which is the force that causes the fiber sliver to shift horizontally to the left. Needle teeth II (8) and needle teeth IV (10) together apply force F2 to the fiber sliver, which is the force that causes the fiber sliver to shift horizontally to the right.

2. The fiber sliver drawing device according to claim 1, characterized in that, When the needle tooth I (7) moves to the bottom, the needle tooth I (7) moves vertically downward. The minimum distance between the needle tooth I (7) and the edge of the upper flexible needle band (5) gradually increases along the running direction of the upper flexible needle band (5). The needle tooth III (9) moves synchronously to the top. The needle tooth III (9) moves vertically upward. The minimum distance between the needle tooth III (9) and the edge of the lower flexible needle band (6) gradually increases along the running direction of the lower flexible needle band (6). The needle tooth I (7) and the needle tooth III (9) intersect each other. When the needleless section of the upper flexible needle belt (5) reaches the bottom, the needleless section of the lower flexible needle belt (6) simultaneously reaches the top. When needle tooth II (8) moves to the bottom, needle tooth II (8) moves vertically downward. The minimum distance between needle tooth II (8) and the edge of the upper flexible needle band (5) gradually decreases along the running direction of the upper flexible needle band (5). Needle tooth IV (10) moves synchronously to the top. Needle tooth IV (10) moves vertically upward. The minimum distance between needle tooth IV (10) and the edge of the lower flexible needle band (6) gradually decreases along the running direction of the lower flexible needle band (6). Needle tooth II (8) and needle tooth IV (10) intersect each other.

3. The fiber sliver drawing device according to claim 2, characterized in that, The spacing between the same row of needle teeth I (7) or the same row of needle teeth II (8) along the width direction of the upper flexible needle strip (5) is 0.05-0.1mm. The spacing between two adjacent rows of needle teeth I (7) and needle teeth II (8) along the length direction of the upper flexible needle strip (5) is 1.1-5.6mm. The spacing between the same row of needle teeth III (9) or the same row of needle teeth IV (10) along the width direction of the lower flexible needle strip (6) is 0.05-0.1mm. The spacing between two adjacent rows of needle teeth III (9) and needle teeth IV (10) along the length direction of the lower flexible needle strip (6) is 1.1-5.6mm.

4. The fiber sliver drawing device according to claim 2, characterized in that, The extension lines of the intersection of needle tooth I (7) and the upper flexible needle strip (5) and the extension lines of the intersection of needle tooth II (8) and the upper flexible needle strip (5) are all at an angle of 15-20° to the edge line of the upper flexible needle strip (5). The extension lines of the intersection of needle tooth III (9) and the lower flexible needle strip (6) and the extension lines of the intersection of needle tooth IV (10) and the lower flexible needle strip (6) are all at an angle of 15-20° to the edge line of the lower flexible needle strip (6).

5. A fiber sliver drawing device according to claim 4, characterized in that, Needle I (7), Needle II (8), Needle III (9) and Needle IV (10) are all irregular right-angled sector plates. The irregular right-angled sector is composed of two line segments and an arc. One end of the two line segments is connected, and the other end is connected to both ends of an arc. The two line segments are perpendicular to each other. The length of Needle I (7) and Needle II (8) along the length direction of the upper flexible needle strip (5) is 5.5-11.2 mm. The length of Needle III (9) and Needle IV (10) along the length direction of the lower flexible needle strip (6) is 5.5-11.2 mm. The tooth height of Needle I (7), Needle II (8), Needle III (9) and Needle IV (10) is 3-5 mm, and the tooth thickness is 0.01-0.02 mm.

6. The fiber sliver drawing device according to claim 2, characterized in that, The running speed of the upper flexible needle belt (5) is 3.7-7 m / min, and the running speed of the lower flexible needle belt (6) is the same as that of the upper flexible needle belt (5).

7. The fiber sliver drawing device according to claim 1, characterized in that, It also includes an upper drive wheel (11), an upper tension wheel (12), an upper positioning wheel (13), a lower drive wheel (15), a lower tension wheel (16), and a lower positioning wheel (17) located simultaneously between the front roller (1) and the middle roller (2); The upper drive wheel (11) and the upper tension wheel (12) are arranged at intervals along the front-to-back direction. The upper positioning wheel (13) is located below both the upper drive wheel (11) and the upper tension wheel (12). The upper flexible needle belt (5) is simultaneously wrapped around the upper drive wheel (11), the upper tension wheel (12) and the upper positioning wheel (13). The lower positioning wheel (17) is located below the upper positioning wheel (13). The lower transmission wheel (15) and the lower tension wheel (16) are arranged at intervals along the front-to-back direction. The lower positioning wheel (17) is located above both the lower transmission wheel (15) and the lower tension wheel (16). The lower flexible needle belt (6) is simultaneously wrapped around the lower positioning wheel (17), the lower transmission wheel (15), and the lower tension wheel (16).

8. A fiber sliver drawing device according to claim 7, characterized in that, It also includes an upper cleaning roller (14) and a lower cleaning roller (18); the upper cleaning roller (14) is located above both the upper drive wheel (11) and the upper tension wheel (12), and the lower cleaning roller (18) is located below both the lower drive wheel (15) and the lower tension wheel (16).

9. A fiber sliver drawing device according to claim 8, characterized in that, It also includes an upper comb needle box (3) with no sealing surface at the bottom and a lower comb needle box (4) with no sealing surface at the top; the upper cleaning roller (14), upper drive wheel (11), upper tension wheel (12) and upper positioning wheel (13) are all located in the upper comb needle box (3); the lower positioning wheel (17), lower drive wheel (15), lower tension wheel (16) and lower cleaning roller (18) are all located in the lower comb needle box (4).

10. A fiber sliver drawing device according to claim 1, characterized in that, The linear velocity of the middle roller (2) is 3-6 m / min, and the ratio of the linear velocity of the front roller (1) to that of the middle roller (2) is 3-8 times.

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